I've got a first gen wifi-only iPad, and I've never regretted not getting 3G. The iPad is mostly a lean-back device for me, and of all the places where I spend more than a few minutes and want a lean-back device I also have wifi.
Once the carriers announce shared internet plans, I MIGHT consider a 3G/4G iPad, but not before then. My wife and I are already paying $60/month for network access, I'm not willing to purchase network access a third time.